1. Field of the Invention
The present invention relates to an image forming system, a method for controlling an image forming system and a non-transitory computer readable storage medium that stores a program for controlling an image forming system, and specifically relates to controlling operations for appropriately implementing a paper sheet processing in an image forming system.
2. Description of Related Art
Recently, various kinds of image forming systems in each of which an image forming apparatus and at least one of various kinds of paper sheet processing apparatuses are coupled to each other has been increasingly proliferated in the printing field. This kind image forming system makes it possible to implement various kinds of bookbinding processing, and can be employed as a printing apparatus. For instance, the saddle stitch bookbinding can be achieved by applying a staple processing to a folded portion of a middle-fold bunch of paper sheets, which is created by folding a bunch of paper sheets along a center line thereof. Further, the spine portion can be created by applying a pressure onto the folded portion of the saddle-stitched bunch of paper sheets so as to create two fold lines that may form a rectangular shaped spine portion. The above-mentioned processing for forming the spine portion of the bunch of paper sheets is called a “spine processing”, which makes the bunch of paper sheets in a state similar to a “perfect binding”.
Further, as a pre-processing to be applied before forming the fold line above-mentioned, a creasing apparatus, called a creaser, is employed for applying a crease processing to the position onto which the fold line is planned to be formed so as to form a crease thereon. Then, by applying the fold processing to the bunch of paper sheets after the crease processing has been completed, it is possible to advantageously prevent the folded portion from swelling up, even when the fold processing is applied thereto in a state of bundling a plurality of paper sheets.
In addition, by implementing the crease processing before forming the fold line as above-mentioned, it is also possible to acquire such an effect that toner, forming a partial image on the folded portion of the paper sheet, is prevented from peeling off therefrom.
In this connection, with respect to the crease processing as aforementioned, each of Japanese Patent Application Laid-Open Publication No. 2012-111619, Japanese Patent Application Laid-Open Publication No. 2012-101872, Japanese Patent Application Laid-Open Publication No. 2012-82052, Japanese Patent Application Laid-Open Publication No. 2012-76883, Japanese Patent Application Laid-Open Publication No. 2012-143899, etc., sets forth various kinds of the related technologies.
In the crease processing described in the foregoing, due to the relationship with the arrangement of the image formed on the paper sheet, a paper sheet reference position (one side of the paper sheet) of the paper sheet is designated. Then, the crease attaching position is designated by using a designated distance “d” defined as a distance between the paper sheet reference position and the crease attaching position.
Successively, the paper sheet processing apparatus makes an apparatus reference position of a stopper or the like coincide with the paper sheet reference position designated, and then, moves a crease attaching unit to a position being apart from the stopper by the designated distance “d”, so as to make the crease attaching unit implement the crease processing at the moved position.
However, depending on the image forming system actually installed, sometimes, such a case that it is impossible to coincide the apparatus reference position with the paper sheet reference position, above-designated, may occur, due to the direction of paper sheets currently accommodated into the paper sheet feeding section and/or the relationship with another paper sheet processing. Incidentally, herein, it is assumed that a paper sheet length in the same direction of the designated distance “d”, above-mentioned, is established as “D”. In such the case as above-mentioned, the crease processing can be implemented by making the other side line, being opposite to the paper sheet reference position (inclined angle between them is 180°), coincide with the apparatus reference position of a stopper or the like, and then, moving the crease attaching unit to a position being apart from the stopper by distance “D-d”.
In this connection, generally speaking, in almost of all cases, one side of the paper sheet, which is nearest to the crease attaching position, is established as the paper sheet reference position. In this case, even if the fixing process causes a shrinkage of the paper sheet size (hereinafter, also referred to as a paper sheet size-shrinkage), an error in the crease attaching position is relatively small. On the other hand, in a case where the crease processing is implemented by making the other side line, being opposite to the paper sheet reference position designated (inclined angle between them is 180°), coincide with the apparatus reference position, and then, moving the crease attaching unit to a position being apart from the stopper by distance “D-d”, the paper sheet size-shrinkage, caused by the fixing process, would considerably influence the crease attaching position to a greater degree than the above case. As a result, the error in the crease attaching position may be getting larger than ever.
For instance, let us assume such a case that the paper sheet processing is to be applied at a position being apart from the paper sheet reference position by 10 mm. In this case, assuming that the paper sheet size is shrunk to the 4% reduced size due to the heat applied to the paper sheet for achieving the fixing operation, the amount of influence, generated at the paper-sheet processing implementation position, is estimated as 10×0.04=0.4 mm.
On the other hand, assuming that the paper sheet length is 297 mm, in a case of implementing the paper sheet processing by employing the other side line, being opposite to the paper sheet reference position designated, as the apparatus reference position, it is necessary to apply the paper sheet processing at a position being apart from the opposite side by the distance estimated as 297 mm-10 mm=287 mm, whereas the reduced paper sheet length after the shrinkage is estimated as 297×(1-0.04)=285.12 mm. Accordingly, since the position at 287 mm is out of range of the paper sheet area, arisen is such a problem that it is virtually impossible to implement the paper sheet processing concerned.
Alternatively, in a case where the paper sheet length is 297 mm and the paper sheet processing is implemented by employing the other opposite side as the apparatus reference position, it is necessary to apply the paper sheet processing to the position being apart from the opposite side by the distance estimated as 297 mm-10 mm=287 mm. Herein, assuming that the paper sheet size is shrunk to the 3% reduced size due to the heat applied to the paper sheet for achieving the fixing operation, the reduced paper sheet length after the shrinkage is estimated as 297×(1-0.03)=288 mm. Owing to this reason, the paper sheet processing is actually applied to the position of 287 mm relative to the total length of 288 mm of the paper sheet, namely, to the position being apart from the edge portion of the concerned paper sheet by 1 mm.
In this connection, degree of the paper sheet size-shrinkage, caused by the fixing process, varies depending on the fixing temperature and the kind of paper sheet. For this reason, it is impossible to correctly estimate a size change of the paper sheet in advance. Accordingly, in a case where the paper sheet processing is implemented by employing the other side of the paper sheet, being opposite to the paper sheet reference position, as the apparatus reference position, arisen is a problem that it becomes impossible to correctly manage the paper-sheet processing implementation position.
Further, although Japanese Patent Application Laid-Open Publication No. 2012-11619, aforementioned, sets forth the controlling operations for controlling the crease processing, no description in regard to the paper-sheet processing implementation position or the various kinds of reference positions as described in the foregoing can be found therefrom (in other words, the concerned Publication pays no attention to the above-mentioned aspects).
Still further, although Japanese Patent Application Laid-Open Publication No. 2012-82052, aforementioned, includes the descriptions in regard to the operations for controlling the conveyance paths of both the paper sheet to which the crease processing is to be applied and the other paper sheet to which no crease processing is to be applied, the concerned Publication pays no attention to the paper-sheet processing implementation position or the various kinds of reference positions as described in the foregoing.
Still further, although Japanese Patent Application Laid-Open Publication No. 2012-76883, aforementioned, includes the descriptions in regard to the operations for heightening the matching aspects between the crease processing and the other kinds of paper sheet processing, the concerned Publication pays no attention to the paper-sheet processing implementation position or the various kinds of reference positions as described in the foregoing.
Yet further, Japanese Patent Application Laid-Open Publication No. 2012-143899, aforementioned, sets forth the controlling operation for rotating an image at 180° as needed, corresponding to the relationship between the edge portion of the paper sheet, which is to be exposed outside as a result of implementing the three fold processing, and the top-and-bottom of the image concerned. However, Japanese Patent Application Laid-Open Publication No. 2012-143899, concerned, pays no attention to the paper-sheet processing implementation position or the various kinds of reference positions as described in the foregoing.